Many computers, as well as other high frequency electrical apparatus or equipment, are sources of significant electromagnetic radiation. As a result, there exists extensive legislation regulating the amount of electromagnetic interference ("EMI") which can be emitted from such equipment. In order to meet or comply with EMI regulations, therefore, manufacturers must provide electromagnetic shielding on equipment enclosures. While effective, electromagnetically shielded electrical equipment enclosures will nevertheless require openings for the communication of input and output signals to and/or from the electrical circuit within the enclosure. Thus, the shielded enclosures routinely are provided with input/output openings through which input/output electrical and/or optical cables are connected, often by a releasable connector assembly.
In recent years, it has become highly desirable for various reasons to communicate into and out of such high frequency electrical apparatus, using optical communication cables. Thus, a fiber-optic cable will be releasably connected through an opening in the enclosure or chassis wall to an electro-optical transducer assembly positioned inside the enclosure and electrically coupled to the apparatus circuitry. If the two-way communication of signals is required, an electro-optical transceiver is employed, but as used herein, the expression "transducer" shall broadly include both electro-optical transducers, suitable for one-way communications, and electro-optical transceivers, suitable for two-way communications.
Electro-optical transducers include their own electrical circuitry, which often operates at a significantly higher switching frequency than the other electrical circuit functions in the equipment. Thus, a computer may operate at a clock or bus switching frequency of 250 MHz, while the electro-optical transducer coupled to the computer electrical circuit is operating at 500 MHz or more. Moreover, the transducer assembly will be a source of harmonic energy radiation at frequencies up to the 5 to 6 GHz range for a fundamental clock rate of 500 MHz. EMI problems increase as the radiation source frequency increases since containing the radiation becomes more difficult as the frequency wavelength shortens and smaller and smaller circuitry elements become effective antennas and smaller enclosure features become antennas.
Shielding the basic high frequency electrical circuit, therefore, is not enough; steps also need to be taken to shield communications transducers and to minimize the size and number of openings which are present in the enclosure for the electrical apparatus to accommodate such transducers. Still further, communication cables for electrical apparatus must be easily disconnected from and connected to the electrical apparatus, and they must be capable of withstanding axial and transverse loading during normal use without becoming mechanically or optically uncoupled from the basic system circuitry.
Prior art electro-optical connector assemblies are known in which the mating connector blocks are employed to join a fiber-optic cables together at the computer chassis wall. Such systems, however, have employed undesirably large openings through the computer wall or have positioned the electro-optical transducer assembly undesirably close to the opening for the cable, or both. Prior connector assemblies for electro-optical transducers also have contained ungrounded or protruding metal components which can re-radiate energy present in the transducer assembly. Other disadvantages of prior electro-optical connector assemblies have included their high cost, difficulty in maintaining optical alignment, and large size (which limits the number of input/output connections).
The present invention solves many of these problems and drawbacks of current electro-optical connectors with a design that is relatively elegant in its simplicity, easy and inexpensive to manufacture, and reliable in its operation.